The present invention is directed to a metal guide member for fastening members to be driven into a hard receiving material by an explosive powder charge driven setting tool. The guide member has a through opening with a guide arrangement for guiding the fastening member as it is driven.
Fastening members driven into hard receiving material by explosive powder charge operated setting tools to secure structural components to the surface of generally hard receiving material are known. The fastening members are used for securing plates or wooden strips or the like and the fastening members have a flange-like head or first end and an opposite tapering second end. A guide member is positioned on the tapering end and is displaced during the driving operation along the shank of the fastening member toward the flange-like first end causing a widening of the through opening. The outside dimension of the guide member is greater than the outside diameter of the flange-like head, so that the tensile forces emanating from the fastened components can be transmitted across a large surface to an attachment member.
As it is known, the attachment member is a guide member in the form of a disk seated on the tapering end of the fastening member, and the attachment member has a central through opening with a square cross-section. The greatest diagonal width of the through opening corresponds essentially to the diameter of the shank of the fastening member.
As the fastening member is driven, the disk is displaced from the tapering second end of the fastening member toward the flange-like first end. During the driving operation the central through opening, especially the side of the through opening is widened by the shank of the fastening member, whereby the contact surface between the shank of the fastening member and the inside surface of the through opening increases considerably. As a result, there is the disadvantage that the force required to widen the through opening is very rapidly distributed across a large contact surface, so that further widening of the through opening is practically impossible. A further disadvantage is that an increased friction is generated by the increasing contact surface and acts counter to the driving of the fastening member.